Beijing, China - Walking into the "sports dome" at Dulwich College Beijing, an elite fee-paying international school in the capital's Shunyi District, one's ears pop and the oppression of the city's air begins to lift.
The school has built the dome - a large airtight, inflatable structure that covers the size of about four badminton courts - to provide an area for indoor sports during the freezing winter months.
But more recently, it has also become a refuge from Beijing's often heavily polluted air when temperatures are more benign, providing expensive relief from the city's high levels of pollution for those children whose parents can afford it.
"It made sense for us so that we could control the air quality indoors; this is even more important when children are exercising," explained the school's head of external relations, Cynthia Maclean. "We added extra air filters, and these filter out particles of 2.5 microns in diameter and above."
One day last week, the dome was being put to good use, providing a bright and breezy venue for volleyball lessons, as the sky outside creaked and palled under the weight of the pollution. Signs inside the school issued the stark warning: "Pollution levels are very high, stay inside."
Others have been quick to follow Dulwich's lead, with the similarly expensive International School of Beijing, where yearly high school tuition fees reach 219,960 RMB (around $35,300), recently opening two of its own domes, each large enough to incorporate office space.
For its part, Harrow International School of Beijing has gone the extra mile in building its new campus. "The biggest single item of expenditure has been the air filtration system, which is integral to all the internal environments from the gym to the classroom," the school's head of marketing, Joanna Scaramella, told Al Jazeera. "Although expensive, this was seen as critical in building a school here in Beijing."
The problems with Beijing's air quality are nothing new. Before the Olympics in 2008, Beijing launched an extensive campaign to clean up the city's air in a bid to create a suitable environment for athletes and visitors, closing down factories and restricting traffic.
"There's certainly a real cost to the economy, whether it's the flow of talent relocating or the cost of installing equipment to pacify patrons or staff."
- Julian Wong, editor at Green Leap Forward
But the past month has also seen an unprecedented wave of public interest in fighting air pollution.
In part, awareness has risen following the government's decision to start publishing PM2.5 readings - an air quality measure that monitors particles of 2.5 micrometres or less in diameter - for cities across China.
The real kicker, however, seems to have been a near month-long bout of toxic smog that enveloped the city, during which the US embassy's air quality monitor reading burst beyond the confines of its usual one-to-500 scale to touch the hazardous level of 900.
"The discussion over PM2.5 turned from scientific terminology to dinner table talk that everyone understands," said Li Yan, Greenpeace's head of climate and energy campaigning in Beijing.
Media reports indicate companies including Apple, Toyota, Honda and JPMorgan Chase began issuing facemasks to their employees, while a straw poll found that firms including BMW, the boutique Opposite House hotel and a handful of small start-ups were ordering from a rapidly dwindling supply of air purifiers for their offices and guest rooms.
Aside from the costs of installing new equipment to keep guests and staff happy, the pollution has taken a toll on the city's reputation.
Ben Leary, CEO of consultancy firm Column Associates, said that while multinational firms did not give its employees a "hardship allowance" for living in Beijing, it has become increasingly tough to attract talent to the city. "We just lost a deal because the wife of a potential client in Hong Kong poo-pooed the move to Beijing because it's so polluted," he said.
Julian Wong, the editor at Green Leap Forward and a long-time observer of China's environmental issues, agreed with Leary. "There's certainly a real cost to the economy," he said. "Whether it's the flow of talent relocating or the cost of installing equipment to pacify patrons or staff."
Wong also believes that the recent continuous flow of stories relating to the pollution, even though the worst of the smog recently lifted, could be a watershed moment.
"The general citizenry is getting the sense that they can be part of certain things," he told Al Jazeera. "The exponential growth of social media has served as a kind of echo-chamber for public concerns, particularly on the environment."
In a seeming acknowledgement of this trend, the local government is currently taking submissions from Beijing's 20 million residents on how it should address the capital's particulate pollution problems.
"Things are moving are really fast - even within the last two years - and the government is trying to catch up with the level of public outcry and expectation."
- Li Yan, Greenpeace climate activist
"This comes amid a broader context of civil discontent and protests related to environmental issues," explained Wong. "People are beginning to believe that they have a say and a right to voice their basic needs to the government."
Beijing has taken a lead on drawing up measures to allay its pollution issues, according to Greenpeace's Li. The city is the first in China to issue its own Clean Air Initiative, under which it will seek to reduce the levels of coal burned in the municipal area to 20 million tons a year by 2015, and 15 million by 2020, compared with the 27 million tons consumed in 2011.
Yet for many people, these measures and others aimed at cutting PM2.5 levels are too little too late.
"The public is asking very specific questions about what exactly is causing the haze, and who is to blame," Li says. "The anger is now directed at the state-owned enterprises that are likely preventing an improvement in standards."
Elsewhere, opinion leaders on domestic television and on social media are calling for China to institute a federal version of the Clean Air Act, and there is some hope that next month's National People's Congress may herald the unveiling of revisions to the country's Air Pollution Prevention Law.
"Things are moving are really fast - even within the last two years - and the government is trying to catch up with the level of public outcry and expectation," Li said, adding that, despite Beijing's position at the forefront of national measures to combat air pollution, Greenpeace has found local officials' levels of understanding of the issues to be "pretty weak".
In the face of such marked public antipathy, pressure on Beijing officials might compel them to find durable solutions to the issues at hand.
If not, it may be the first city in history where clean, purified air is a commodity available only to those few with the means to afford it.